Heretofore, in the replacement of a boiler tube or the retubing of a water-tube boiler, air hammers have been conventionally utilized to remove the boiler tubes from their secured friction fit relation in their associated openings in the boiler drum. Such use of air hammers not only requires substantial skill in order to not do considerable damage to the boiler drum; however, even when utilizing substantial care, the air hammers gouge out and deform the openings in the associated drum in which the tubes are mounted. Such conventional retubing process takes considerable time and is quite expensive. Also the damage done to the boiler drum and tube openings therein by the air hammer has to be repaired, utilizing welds and the like, all of which contributes to a resultant relatively expensive procedure.